Development of Hybrid Silicon Lasers Takes Flight

The Air Force Research Laboratory (AFRL) approved a Cooperative Research and Development Agreement with the Nanoelectronics Materials Branch and Iris Light Technologies that will focus on the development of hybrid silicon lasers.

Success in getting silicon chips to emit significant amount of light has been recent, but limited. A process that alloys silicon with germanium advanced the technology, though the process is tedious and expensive.

Dr. Chad Husko, CEO and founder of Iris Light, holds a 300-mm silicon wafer. Courtesy of Iris Light.

According to AFRL research scientist Steven McKeown, who is part of a team seeking to develop hybrid devices that integrate lasers with silicon chips, “The problem is that silicon has poor optical gain — gain being how we get ‘lasing.’”

In part, the new project aims to find a cost-effective and more reliable way to manufacture the on-chip lasers and to enable mass production. One method currently under exploration involves a type of “photonic ink” developed by Iris Light Technologies, AFRL’s partner in the agreement.
The ink is used to print laser gain material directly onto passive silicon chips. Iris intends to modify the ink in such a way that it will emit light when pumped by electrical current. The ink is able to emit light over a broad spectrum, ranging from visible to near-infrared.

“The ink will be what converts the energy into the laser light,” McKeown said. “The thing that actually kind of shapes the light and carries it and guides it is the silicon. It interacts with the ink in that it converts energy into laser emission.”

The technology would have broad applications, though the partners note computer technology in particular, due to the level of resistance to the flow of electrons in copper wire, which produces heat. Using photonic technologies would increase speed and reduce power consumption, especially with tighter integration, McKeown said.

Other applications of interest to AFRL are hyperspectral imaging, lidar, and radio frequency photonics.

“So researchers are looking at everything, and not every solution may apply to every problem. We may end up with a toolkit that has several solutions, or we may end up with one solution for all problems,” McKeown said.